The present invention generally relates to the collection of breast milk and specifically to an improved suction bell for a breast pump and to an insert or liner for such a suction bell.
Breast pumps of various designs have been known since early in the twentieth century and a large number of patents relating to that subject matter have issued since. Common features of such devices are a generally flared member (commonly termed a xe2x80x9csuction bellxe2x80x9d) adapted to encompass the nipple region of a mother""s breast, a source of cyclic sub-atmospheric pressure (also termed a suction device or pump), and milk collecting means usually in the form of a bottle.
Obviously, an essential factor, both with regard to a user""s comfort as well as to stimulation of the lactation process are the feel of the suction bell when in contact with a breast and the impact of the cyclic pressure changes. In line with these requirements, U.S. Pat. No. 2,542,505 (to G. H. Gascoigne) discloses a shell made of metal and consisting of a recessed disc-like head connected with a conical body provided with a central hub, and an elastic liner connected with the conical body at the liner""s upper and lower ends. Two separate inter-spaces are formed between the liner and the shell; a first inter-space is formed between the hub, the disk near its front face, and the liner, and a second inter-space is formed between the liner and the conical portion of the shell""s body.
The aim of the the Gascoigne device is to simulate natural actions produced by the facial movements and mouth suction of a suckling baby by pneumatically-produced pulsation. To that end, periodic pressure pulses are applied at the first inter-space while suction pulses are applied both inside the liner as well as inside the second inter-space; in other words, suction pulses are combined weith pressure pulses.
However, the Gascoigne device was not and is not suitable for practical use for a variety of reasons. First, its complicated structure would be costly with regard to production and maintenance. Second, and even more essential for user acceptance, is the virtual impossibility of cleaning and sterilizing the device between uses by normal means available in a household. Other disadvantages result from the need to apply both pressure and suction pulses, requiring three pneumatic lines, one for continuous suction applied inside the liner and acting directly upon the breast, and two pulse lines, one for suction pulses and one for pressure pulses applied outside the liner at different portions thereof.
U.S. Pat. No. 4,263,912 (F. H. Adams) discloses milking devices suitable for both humans and cows. The element common to both embodiments is a flexible liner which, in the case of a breast pump, is disposed within a shell with an inter-space formed between the shell and the liner. Suction is applied periodically to the inter-space. While the structure of the breast pump embodiment is relatively simple, compared with Gascoigne, cleaning and safe sterilization are not easily possible. So, again, this device has not, to the best of applicant""s knowledge, been widely accepted, nor has another device disclosed by the same inventor in U.S. Pat. No. 4,323,067 which requires two suction means and where the suction bell is made of an elastic material and integrally forms a membrane-closed suction chamber for periodic suction pulses.
Accordingly, it is an object of the present invention to provide an improved suction bell for a breast pump that avoids the aforementioned drawbacks of prior art suction bells by means of a simple and effective structure for simulating a normal suckling action when operated, and which can be easily assembled and disassembled for cleaning and sterilization by means readily available in the home, that is, by immersion in boiling water.
Another object is to provide a suction bell that meets the above objects yet can be manufactured at low cost.
A still further object is to provide a suction bell that can be used with a variety of breast pumping devices, including electrically-operated pumps and manually-operated pumps.
Yet another object of the invention is to provide an integral or monolithic liner that can be easily mounted in and disassembled from a rigid shell for a suction bell while providing the following advantages: optimum contact with a mother""s breast for stimulating the flow of milk and for simulating the mouth action of a nursing infant; smooth withdrawal of milk while preventing direct exposure of the milk to air flowing to and from the pumping means; easy and simple cleaning and sterilization of the liner and shell apart from each other and apart from other components of the breast pump assembly; and low production costs. With respect to the latter, it is a specific object to provide a one-piece liner and valve combination that can molded in its entirety from a suitable elastomeric material with a minimum of processing steps.
Briefly, and according to a first general embodiment, the suction bell comprises a rigid outer shell that is generally funnel-shaped, that is, one that is substantially Y-shaped in longitudinal section, having a conical top portion with an open upper end and a cylindrical body portion with an open lower end. The conical top portion of the shell has an outwardly extending rim at its upper end and the cylindrical body portion has first connecting means for connecting the interior of the shell with a source of cyclic sub-atmospheric pressure such as, for example, a conventional manually- or electrically-operated pump, such as a membrane pump. The lower end of the shell is provided with an annular shoulder and is detachably joined to connecting means for attachment to a standard milk collecting receptacle (bottle).
A thin, flexible elastic liner is detachably mounted within the shell, the liner having a conical upper portion disposed within the conical top portion of the shell and provided with a peripheral lip for sealingly engaging the shell""s rim. The liner also includes an elongated tubular portion that extends through the shell""s cylindrical body portion and has an outer surface spaced inwardly from the shell""s inner surface when the pressure within the cylindrical body portion of the shell is at ambient or atmospheric pressure. The tubular portion of the liner includes a resilient annular flange that sealingly engages the shoulder of the shell so that the liner is held in an axially stretched and tensioned state between its upper and lower connections with the shell. Further, the liner includes an integral one-way valve at the lower end of the liner""s tubular portion and below the shoulder of the shell. In a preferred embodiment, the valve has a calotte-shaped end portion with at least one slit that has offset portions extending from opposite inner and outer surfaces, resulting in a one-way valve structure that opens easily to allow the flow of milk, seals effectively when the pressure external to the liner is reduced, and may be inexpensively manufactured with a minimum of production steps. In a further embodiment, the calotte-shaped end portion of the valve has a pair of crossed slits, each with offset portions wich provide the described advantages. The offset of the slit portions allow the slit or slits to be formed at the time the liner is molded rather than in one or more subsequent cutting operations.
The conical upper portion of the liner is provided with a multiplicity of coaxial corrugations for contacting the breast in the area of the nipple, such corrugations promoting effective sealing against the breast without sticking to the skin and tending to spread and contract during operation of a breast pump in a manner that is believed to stimulate and enhance the flow of milk.
In a further embodiment of the invention, the connecting means for joining the rigid funnel-like shell to a collection receptacle (bottle) permits swivel action of the shell to increase user comfort and help insure proper sealing contact between the conical portion of the resilient liner and the user""s breast.
Other features, objects and advantages will become apparent from the specification and drawings.
The term xe2x80x9crigidxe2x80x9d as used herein in reference to the structure of the shell is intended to refer in a relative sense to a material that will show no substantial deformation when the bell is exposed to alternating air pressures and other forces in normal use.
The term xe2x80x9cupperxe2x80x9d (or xe2x80x9cupstreamxe2x80x9d) is intended to refer, again in a relative sense, to the flared open end of a Y-shaped (or funnel-shaped) structure oriented so that the single tubular leg of the Y, or the narrowest part of the funnel, is at the xe2x80x9clowerxe2x80x9d end thereof.
The term xe2x80x9celongatedxe2x80x9d as used herein refers to a structure that is longer than it is wide, e.g., has a length of at least twice its width.
xe2x80x9cSealingxe2x80x9d as used herein refers to the connections between the upper and lower portions of the liner with the upper and lower parts, respectively, of the rigid outer shell and indicates a normally air-tight or hermetic connection.
xe2x80x9cSub-atmospheric pressurexe2x80x9d is an absolute pressure that is lower than ambient pressure at the site of use of the invention and is used interchangeably with xe2x80x9csuctionxe2x80x9d or xe2x80x9cvacuum.xe2x80x9d Typical absolute sub-atmospheric pressures for use according to this invention are in the general range of from about 50 to about 500 millibar (mbar) which correspond to relative pressures in the range of minus 950 to minus 500 mbar. The extend of pressure reduction is not considered critical for reasons of the self-limiting effect provided according to the invention; that is, the impact of suction upon the breast is limited by the volume of the space provided for expansion of the elastic liner within the rigid shell.
The term xe2x80x9caboutxe2x80x9d is intended herein to include deviations of a numeric value preceded by this term of xc2x120% of the value given.
The phrase xe2x80x9ca thin, flexible and elasticxe2x80x9d material is used herein to define the nature of the liner material and is intended to refer to a soft, organic and preferably synthetic material having a thickness in the range from about 50 to 1000 xcexcm micrometers) and which is capable of being easily folded upon itself without damage and of being stretched at least 20% of its length and fully recovering when the stretching force is removed. Typically, a liner according to the invention will show an essentially linear and reversible stretch of about 20 mm when tensioned by a force of about 700 grams. Obviously, the thickness of the liner may differ between its sealing ends and its breast-contacting central region but can be easily selected by those experienced in the art in view of the required functions as explained in more detail hereinafter.